Re: [gentoo-dev] Things one could be upset about

[Róbert Čerňanský]

On Tue, 20 Jan 2015 00:14:29 +0300
Andrew Savchenko <bircoph@g.o> wrote:

> On Mon, 19 Jan 2015 21:44:25 +0100 Róbert Èeròanský wrote:
> > From my point of view it would do much help if portage resolves USE
> > dependencies automatically instead of telling the user to change USE
> > flags manually (I am talking about bug #258371).
>
> As the user the last thing I want is to have some USE flags changed
> without my permission ending up stuff I need to be omitted or stuff
> I don't want to see on my system to be installed. Of course if
> someone prefers USE flags to be randomly changed I don't mind if
> such option will exist (as proposed in bug #258371) as long as it
> is disabled by default.

Is is of course perfectly fine to have that option disabled by
default.  But I am afraid that I do not quite understand yours and
Daniel's concerns.  If I paraphrase your statement with regards to
current dependency handling, it is as if you were saying: "I do not
want portage to install any package automatically by its own, I want
to install all the dependencies explicitly."

Why we allow portage to install dependencies and still have things
under control?  Well we have --pretend and --ask options and we can
see what would/will be done.  This would be the same with USE flags.
You would see in the --pretend output which flags would be changed.

To match the package dependency handling, there should be also an
option equivalent to --depclean.  It would revert the USE changes
which were done because of dependencies requirements if no longer
needed.

For example, lets have following packages:

- libbar
- libfoo with IUSE=bar, which depends on: bar? ( libbar )
- foo, which depends on: libfoo[bar]

USE flag bar is not enabled.  You want to install application foo.

Current behaviour:

# emerge -av foo
...
Required USE changes:
libfoo +bar
... (sorry for not exact emerge output but you get the idea)

Now, you either fire up your favorite editor and add "libfoo +bar" to
/etc/portage/package.use, re-run emerge and have libbar installed even
you do not want it.  The other option is not to install application
foo at all.

If you choose to emerge it and after year or so you decide to unmerge
it because you do not need it anymore you still will have a leftover
in package.use file - the line "libfoo +foo" even if you run emerge
--depclean.

New behaviour with automatic USE dependencies resolution:

emerge -av foo
[ebuild  N     ] libbar
[ebuild  N     ] libfoo +bar
[ebuild  N     ] foo

Now, you can hit Y if you agree what portage wants to do or N and not
to install foo at all.

After unmerging it you run emerge --depclean which removes libfoo with
its changed USE flag and libbar, no leftovers. (In this case new
--use-depclean command is not required since libfoo was removed.)

If libfoo would not be removed because some other package needs it,
then emerge --use-depclean would revert the +bar USE flag to its
default state and re-emerge libfoo.

Robert


-- 
Róbert Èeròanský
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